Eating an egg a day is OK

By Dr. Liji Thomas, MDMar 4 2020

A new study and meta-analysis released by the Harvard T. H. Chan of Public Health shows that it is safe to eat up to 1 egg a day without worrying about whether it is harming the health of the heart and blood vessels. The study was published online on March 4, 2020, in the journal BMJ.

Many scientists have reported conflicting data on the role of eggs in human nutrition over the last few decades. In fact, three different studies have been published over the last year – the only issue is that all reached varying conclusions.

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The study

The current study follows up an earlier piece of research published in JAMA (1) in 1999, which looked at the intake of eggs and heart disease. That research failed to find a link between the two.

In this study, the scientists reviewed the health data from over 170,000 women and 90,000 men, all participating in the Nurses’ Health Study (NHS) I and II, and in the Health Professionals Follow-Up Study (HPFS).

All participants were nondiabetic and had no evidence or history of strokes, heart attacks, or other cardiovascular diseases. They also had no history of cancer.

The researchers examined the dietary pattern as many times as possible over the 32 or less years available, to get a clear idea of how the participant ate, especially if the person was obese or ate much red meat. That helped them evolve a large meta-analysis, the biggest ever conducted so far. It included 28 groups of people and 1.7 million individuals.

The findings

The researchers found, from their examination of the data from the NHS and the HPFS groups, that moderate egg intake is not associated with increased cardiovascular risk. The findings apply mostly to European and US populations, but concerning Asians, eating eggs in moderate amounts could reduce the risk of cardiovascular disease. However, this could have been the result of vastly different lifestyles.

The findings run counter to a hugely influential earlier study published in JAMA (2) which reported that eating more eggs were linked to a higher risk of CVD and early death. That reiterated earlier fears related to egg consumption, even though these had been largely removed by federal dietary guidelines that dropped all caps on daily dietary cholesterol intake on the grounds of insufficient evidence that eating more cholesterol was linked to heart disease.

The study calculated an increased risk of 6% and 8% for CVD and early death, respectively, for each extra half-egg per day. However, this still does not mean eating eggs is unhealthy, just that eating more eggs than the current American average of 3-4 eggs a week is riskier.

Earlier, a 2018 study in the journal Heart (3) showed that having one egg a day, on average, led to a 12% lowering in the rate of heart disease and a 26% lower chance of hemorrhagic stroke compared to non-egg-eaters.

Implications

One possible explanation for the mixed messages about egg consumption may be that eggs are eaten more often as part of an unhealthy lifestyle, which means those who regularly eat more eggs are also more likely to consume more unhealthy foods such as butter and cheese, and less likely to exercise appropriately.

Egg whites are often recommended as they supply high-quality protein and do not contain cholesterol. However, the yolks supply amino acids, iron and choline, besides non-saturated cholesterol, as well as a right amount of vitamin A and vitamin D. In the light of this valuable dietary input, it would probably be wise to steer clear of extra eggs if one has a family history or a high-risk personal history for CVD.

Researcher Shilpa Bhupathiraju says that eggs can be consumed as part of a healthy eating pattern in moderation but are not essential. Instead, she points out, “There is a range of other foods that can be included in a healthy breakfast, such as whole-grain toasts, plain yogurt, and fruits.”